The present invention has been proposed in view of the above problems. Embodiments of the invention may exhibit certain advantages in comparison with prior art devices.
An embodiment of the invention may provide a reclining device capable of eliminating mechanical play in a front and rear direction in a seat back during normal operation. The reclining device may perform reliable locking and releasing at a low cost.
An embodiment of the invention may provide a low cost reclining device that can prevent unintended inclination movement of the seat back in an emergency such as a vehicle collision or the like, with a simple structure.
In order to solve the above problems, embodiments of the invention may employ various structures.
The invention may be embodied in a reclining device that includes a base plate fixed to either of a seat cushion or a seat back, and a gear plate with inner teeth that is rotatably assembled with the base plate and fixed to the other of the seat cushion or the seat back. Two pairs of fixed guides may be formed on the base plate. One of two lock gears, each of which has outer teeth that are capable of being engaged with the inner teeth of the gear plate, may be located between each pair of fixed guides so that the lock gears can slide along one of the fixed guides. The device may include a cam that controls the movement of the pair of lock gears to engage the lock gears with the inner teeth of the gear plate. Springs can be provided to impart a rotational force to the cam to keep the lock gears engaged with the inner teeth of the gear plate. A center shaft 70 can be configured to drive the cam to rotate and hereby to disengage the pair of lock gears from the gear plate. A movable guide can be slidably disposed between each of the lock gears and the corresponding pairs of fixed guides. Each of the movable guides can be formed in a shape the width of which gradually decreases from the outer end toward the inner end, with the pair of movable guides being provided with a spring that imparts a force to the pair of movable guides toward an inner direction of the base plate.
In some embodiments each of the movable guides may be formed in a shape the width of which gradually decreases from the outer end toward the inner end, and arranged so that a sliding face at the side of the lock gear is parallel to a movement direction of the lock gear and so that a sliding face nearer the fixed guide is inclined with respect to the sliding face nearer the lock gear.
In some embodiments each of the lock gears may be formed with a width that gradually decreases from the inner end toward the outer end. The sliding face of the lock gear near the fixed guide can be parallel to a movement direction of the lock gear. The movable guide can be formed so that its width gradually decreases from the outer end toward the inner end, and be arranged so that the sliding face near the lock gear is inclined with respect to a movement direction of the lock gear, and so that a sliding face near the fixed guide is inclined with respect to the sliding face near the lock gear.
In some embodiments the spring attached to the movable guides may be a torsion spring that pulls the movable guides at the both ends of the spring toward one another.
Some embodiments may include a pair of torsion springs that impart a rotational force to the cam, in which each of the torsion springs imparts a force to pull the cam and the movable guide attached to that spring together along a diagonal line.
In some embodiments each of the movable guides can be provided with outer teeth capable of being engaged with the inner teeth of the gear plate at the outer end of the movable guides.
In some embodiments each of the movable guides can be formed with a contact portion that comes into close contact with one of the fixed guides at the outer end portion of the sliding face of the fixed guide. A step portion can be included at the contact portion to insure a gap between the fixed guide and the movable guide.
Some embodiments may include a link plate that rotates along with the cam to push the movable guides outward when the cam is rotated, thereby to disengage the lock gears from the inner teeth of the gear plate.
The base plate can be laser-welded to a seat cushion bracket or a seat back bracket that forms a part of a seat frame of a vehicle seat.
A base plate can be fixed to either of a seat cushion or a seat back. A gear plate with inner teeth can be rotatably assembled with the base plate and fixed to the other of the seat cushion or the seat back. Two pairs of fixed guides can be formed on the base plate. Lock gears, each of which has outer teeth capable of being engaged with the inner teeth of the gear plate, can be disposed between the pairs of fixed guides so that the lock gears slide along the fixed guides. A cam can be included to control the movement of the lock gears to engage the lock gears with the inner teeth of the gear plate. A pair of springs can be configured to impart a rotational force to the cam to keep the lock gears engaged with the inner teeth of the gear plate. A center shaft can drive the cam to rotate to disengage the pair of lock gears from the gear plate. The mechanical strength of the fixed guides can be made lower than the strengths of the gear plate and the lock gears so that, when a large load is applied to the reclining device, the lock gears push the fixed guides to deform the fixed guides and cause the outer end portion of the fixed guides to come into contact with the inner teeth of the gear plate to thereby prevent the inclination movement of the seat back.
The fixed guides can be located so that the outer end portions of the fixed guides are positioned close to the front ends of the inner teeth of the gear plate, so that when the fixed guides are deformed, their outer end portions bite into the inner teeth of the gear plate.
The fixed guides can have a thickness such that, when the base plate and the gear plate are assembled with each other, the fixed guides come into substantially close contact with the gear plate, and such that when the fixed guides are deformed, the gear plate restricts the deformation of the fixed guides.
Some embodiments can include a link plate that rotates along with the cam to pull the lock gears inward when the cam is rotated to disengage the lock gears from the inner teeth of the gear plate. The link plate can include a cut-off in an outer periphery at a point where, when the lock gears are engaged with the inner teeth of the gear plate, the lock gears come into contact with the outer end portion of the fixed guides at the outer periphery of the link plate, and when the fixed guides are deformed, the deformation is released from the cut-off of the link plate to allow the link plate to come into contact with the gear plate.
Embodiments of the invention may exhibit the following advantageous effects.
The reclining device can be provided with a pair of movable guides. Each of the movable guides can have a wedge-like shape the width of which gradually decreases from the outer end toward the inner end. Each of the movable guides can be disposed between the lock gear and the fixed guide. Each of the movable guides can be imparted with a force toward an inner direction of the base plate by a spring. So configured, each of the movable guides is sandwiched between the lock gear and the fixed guide 30. The fixed guide, the lock gear, and the movable guide are then maintained in close contact with one another with no gap between them. Consequently, mechanical play in the front and rear direction of the seat back can be reliably eliminated, and the lock gear and the movable guide can be reliably locked with and released from each other.
In some embodiments, each of the movable guides is arranged so that the sliding face near the lock gear is parallel to a movement direction of the lock gear. This can prevent the movable guide from catching against the lock gear. Mechanical play in a front and rear direction of the seat back can also be eliminated, and the movable guides can be reliably locked and unlocked.
The lock gears can be formed so that their width gradually decreases from their inner ends toward their outer ends. The sliding face of each of the lock gears near its fixed guide can be parallel to the lock gear's direction of movement. The lock gear is thereby formed with an inclined surface near the movable guide. The movable guide, which has a wedge-like shape, is disposed between the inclined surface and the fixed guide. The sliding faces are held in a close contact with each other, and the outer teeth of the lock gear engage with the inner teeth of the gear plate. The rotation of the gear plate is thereby locked, and the seat is thus not allowed to recline. To unlock the seat and allow it to recline, the center shaft is rotated to disengage the outer teeth of the lock gears from the inner teeth of the gear plate. The contact face between the lock gear and the movable guide is inclined with respect to a movement direction of the lock gear. When the lock gear is pulled in an inner direction, the lock gear and the movable guide can be separated with very little friction generated between them. The lock gear can thereby be pulled inward smoothly and without significantly pushing out the movable guide with the link plate, and the lock can thus be released. The reclining device can be constructed from only a few component parts.
In some embodiments the movable guides are attached to the respective ends of a torsion spring. The base plate will in that case not require any engagement portions for the spring, and the number of component parts can be reduced and the structure of the device simplified. This facilitates the assembly of the reclining device, which can reduce its cost of manufacture and enhance its durability.
In some embodiments, each of the two torsion springs is attached to a cam at one end of the spring and to one of the movable guides at the other. This configuration pulls the movable guides along a diagonal line. Inward forces are thereby imparted to the movable guides, with a rotational force imparted uniformly to the cam from two directions. The cam is thus not imparted with a force in an eccentric direction. The cam is rotated at the center of the base plate, because the pushing force of the cam 50 is applied uniformly to both of the lock gears. The outer teeth of the lock gears engage with the inner teeth of the gear plate, and locking is reliably achieved.
In some embodiments each of the movable guides will have outer teeth at the outer end of the guide. When an overload is applied to the reclining device during a vehicle collision or the like, a rotational load is transmitted from the gear plate to the lock gears. The lock gears then push the movable guides between the fixed guides. Each of the movable guides is formed with a width that gradually decreases from the outer end toward the inner end. Each of the movable guides is pushed outwardly along the base plate. The outer teeth at the outer end of the movable guides move toward the inner teeth of the gear plate and are engaged with them. The movable guides and the lock gears thereby prevent the gear plate from rotating. When an overload is applied to the reclining device during a vehicle collision or the like, the movable guides and the lock gears thereby prevent rotation of the gear plate, and unintended inclination of the seat back is prevented in the collision.
A gentle two-step shape that includes a contact portion and a step portion can be formed on the movable guide near the fixed guide. The movable guide is thus in close contact with the fixed guide only at the contact portion. Consequently, even when there is some small variance in the manufacturing dimension of the fixed guide, the movable guide naturally comes into close contact with the fixed guide at its outer end. Mechanical play in the front and rear direction of the seat back can thus be prevented.
When the cam is rotated to release the lock, a link plate that rotates along with the cam pushes the movable guides outward. When movable guides with a wedge-like shape, which are in a close contact with the fixed guides and the lock gear, are pushed outward, a gap opens between the movable guide and the lock gear. This allows the lock gear to slide, thereby releasing the lock reliably.
The base plate can be laser-welded to a seat cushion bracket or a seat back bracket that forms a part of the seat frame. Emboss processing points for welding on the base plate can be reduced, and it is not required to form a large opening in the bracket. Plastic processing on the component parts can thereby be minimized, and a high-strength vehicle seat provided.
In some embodiments, the mechanical strength of the fixed guides formed integrally with the base plate 10 can be made less than that of the gear plate and the lock gears. Therefore, when an overload is applied to the reclining device upon a vehicle collision or the like, the lock gears will push and deform the fixed guides. The outer end portions of the fixed guides will thus be brought into contact with the inner teeth of the gear plate 20. This will fix the gear plate in place and prevent the seat back from inclining. Therefore, even in a collision or another emergency, unintended inclination of the seat back can be prevented. Since, moreover, the fixed guides are formed integrally with the base plate, the number of component parts can be reduced and the structure simplified, which makes assembling the device easier. The device's manufacturing cost can thus be reduced and its durability increased.
In some embodiment, the outer end portions of the fixed guides and the front ends of the inner teeth 21 of the gear plate are located as close to each other as possible. Even a small deformation of the fixed guide can thus cause force the outer end portion of the fixed guide into contact with the inner teeth of the gear plate, thereby preventing unintended inclination of the seat back.
In some embodiments, the fixed guides have a thickness that brings them into close contact with the gear plate when the base plate and the gear plate are assembled. The gaps between the base plate and the gear plate in the direction of the shaft axle is thus made as small as possible. Therefore, when the fixed guides are deformed, the gear plate restricts this deformation in the direction of the gear plate's thickness. Nearly all of the deformation of the fixed guide can be utilized to bring the fixed guide into contact with the inner teeth of the gear plate. Consequently, unintended inclination of the seat back can be more reliably prevented.
The link plate of the reclining device can have a cut-off at the peripheral end of the link plate. When an overload is applied to the reclining device in a collision of a vehicle or the like, a part of the deformed lock gear runs out from the cut-off to engage with the gear plate. The movement direction of the material of the deformed fixed gears can thus be controlled as desired, and the fixed guides thereby engaged with the gear plate more effectively.